Remediation of Tenorm Landfill Near TPP Plomin

Full text: TPP Plomin is 125 MW coal power plant located at the end of Plomin bay in Istria region of Croatia. It started operation in 1970 using coal from local mines from nearby Rasa area. The coal is with high content of sulfur and with high radioactivity, mainly due to increased concentrations of uranium-238 and radium-226. In a vicinity of TPP Plomin slag/ash landfill was set up. Present volume of repository is 850.000 m3. Repository is placed on downstream section of the Bizac stream, along the contact zone of proluvial fan of the Boljuncica river. Bottom of the repository is numulite limestone, so characteristics of karst hydrology are present. Radioactivity of coal as well as deposited slag/ash were monitored regularly. Several in situ gamma dose rate measurements on the pile were performed also. For uranium-238 measured concentration was typically 70-2500 Bq/kg (mean value 550 Bq/kg) and for radium-226 from 90-3200 Bq/kg (mean value 800 Bq/kg). During last decade due to public concern local coal was 'diluted' with imported varieties with low radioactivity contents, and recently local mines were closed and only imported coals are used. Measurements are showing that the pile is having pronouncedly uneven distribution of radioactivity concentration. There are no engineering barriers surrounding pile protecting bottom of the repository or the sides. Top of the pile is partially covered with soil and vegetation. The owner of the TPP Plomin is preparing restoration of the landfill. Our Agency prepared guidelines consulting EU directives and IAEA BSS for the restoration project since TENORM waste is not directly regulated by Croatian law. Several interventions are proposed. (author)